US6222069B1ExpiredUtility

Method for purifying adipic acid in water

37
Assignee: RHONE POULENC FIBRESPriority: Jun 4, 1996Filed: May 29, 1997Granted: Apr 24, 2001
Est. expiryJun 4, 2016(expired)· nominal 20-yr term from priority
Inventors:Eric B. HenrietPhilippe LeconteCarl PatoisRobert Perron
C07C 51/43
37
PatentIndex Score
1
Cited by
8
References
10
Claims

Abstract

The invention discloses a method for purifying adipic acid in water. More precisely it discloses an improvement in adipic acid crystallization or recrystallization in water, characterised in that the said crystallization or recrystallization is effected in presence of a strong proton acid and/or in the presence of carbon monoxide. This crystallization or recrystallization particularly enables the content of metal catalyst traces in the adipic acid to be reduced.

Claims

exact text as granted — not AI-modified
What is claimed is:  
     
       1. A process for purifying adipic acid having a minimum purity of approximately 95% and containing traces of a catalyst, the process comprising the steps of: 
       a) dissolving the adipic acid in the presence of at least one of a strong protic acid and carbon monoxide; and  
       b) including crystallization of the dissolved adipic acid.  
     
     
       2. The process of claim  1 , wherein the catalyst comprises at least one of iridium, rhodium, and cobalt. 
     
     
       3. The process of claim  1 , wherein the strong protic acid has a pKa of less than 1. 
     
     
       4. The process of claim  1 , wherein the strong protic acid comprises hydroiodic acid, hydrobromic acid, hydrochloric acid, nitric acid or sulphuric acid. 
     
     
       5. The process of claim  1 , wherein the strong protic acid is present in a quantity ranging between 0 to 100 mol per mole of the catalyst. 
     
     
       6. The process of claim  5 , wherein the quantity is between 1 and 50 mol per mole of catalyst. 
     
     
       7. The process of claim  1 , wherein the carbon monoxide is present under an absolute pressure of 0 to 50 bars. 
     
     
       8. The process of claim  7 , wherein the absolute pressure is between 1 to 50 bars. 
     
     
       9. The process of claim  1 , further comprising seeding the solution of dissolved adipic acid with crystals of pure adipic acid. 
     
     
       10. The process of claim  1 , wherein step a) comprises dissolving the adipic acid in purified water at a temperature of 80 to 250° C.

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